1. Field of the Invention
The present invention relates to a sheet post-processing device, and more particularly to a sheet post-processing device for finishing, for example, binding or stapling sheets ejected from an image forming apparatus such as an electrophotographic copying machine.
2. Description of Related Art
It is known that sheets ejected from an image forming apparatus such as an electrophotographic copying machine are bound into a booklet. Japanese Patent Laid-Open Publication No. 2004-284750 and Japanese Patent Laid-Open Publication No. 2008-214104 suggest that preparatory to folding of a set of sheets, perforations or a fold be made in every sheet.
However, making perforations in every sheet is not good in appearance because the perforations made in the outermost sheet of a booklet are apparent.